1. Technical Field
The invention relates to a fixing device and an image forming apparatus with the same.
2. Related Art
A fixing device that fixes an unfixed toner image formed on a recording medium, such as a transfer sheet, an OHP (overhead projector) sheet, etc., (hereinafter, simply referred to as a sheet) by heat and pressure in an image forming apparatus, such as a copier, a printer, a facsimile machine, etc., is well known. In such a fixing device, a belt fixing system with an endless fixing belt capable of shortening a warm-up time while consuming less power is known.
For example, a belt-fixing device capable of adjusting a condition of a fixing nip to preferably execute fixing is disclosed in JP-2011-59247-A.
However, in a conventional belt-fixing device, in which a heater is installed in a heating roller, because the diameter of the heating roller is relatively large a gap between the heater and the heating roller is also large. Accordingly, an excessive amount of energy is needed to heat the large volume of air inside the heating roller. The above-described fixing device disclosed in JP-2011-59247-A may not resolve this problem of poor energy efficiency.